Why we add 1Rs to a gift sum?

Well there are two type of belief for the coin throw custom (tradition). One is traditional belief i.e. what people believe and other is scientific belief . We will talk about both traditional and scientific (or ancient) belief with some of its history one by one:

◾Traditional Belief (what people think):

It is common in India to give money for weddings and auspicious occasions. It is considered auspicious to add a rupee to the sum total. Most of the people don't know the reason behind this tradition. So, I have done some digging and find out the reason.

◾Scientific (Ancient) Belief:

There is a psycological reason behind this tradition. Let me explain this by example:

These days ecommerce sites are getting very popular. You have noticed one thing, if the price of item contains '0' digit at end then they write it after substracting 1Rs.

Here they have written the price Rs.9999 instead of Rs.10000 because Consumers tend to perceive “odd prices” as being significantly lower than they actually are, tending to round to the next lowest monetary unit. Thus, prices such as $1.99 are associated with spending $1 rather than $2. The theory that drives this is that lower pricing such as this institutes greater demand than if consumers were perfectly rational.

Similarly, if price is 1000/- people says 1000/- but 999/- quick translation goes to 900 something which give impression less than 1000/- (technically its less than 1000/- but by just 1 Rs).

In the similar way, here we are giving money as a gift to other person so we want it to look more than the actual price. So, we add 1.RS to a gift sum. There is nothing auspicious about it. It is just psychological game.